Some microcontrollers include, as part of their core components, a general purpose input/output (GPIO) controller that manages all the I/O pins on the chip. In some cases, a user can specify the function of each I/O pin, which then is configured accordingly by the GPIO controller.
Many microcontrollers have one or more low-power modes, during which core components, such as the GPIO controller are powered off or deactivated so as to reduce power consumption. Although I/O pins having dedicated functions could be coupled directly to the backup power management, for example, by bypassing the GPIO controller, such an arrangement provides limited flexibility in the overall system during low-power modes of operation because the function of each such I/O pin is fixed.